TY - GEN A1 - Ramsauer, Ralf A1 - Duda, Sebastian A1 - Mauerer, Wolfgang A1 - Bulwahn, Lukas T1 - The list is our process: An analysis of the kernel’s email-based development process T2 - Linux Plumbers Conference, Lisbon September 9, 2019 Y1 - 2019 UR - https://www.youtube.com/watch?v=QG1YDQ1HOKE ER - TY - GEN A1 - Ramsauer, Ralf A1 - Kiszka, Jan A1 - Lohmann, Daniel A1 - Mauerer, Wolfgang T1 - Implementierung gemischt kritischer Systeme durch statische Hardwarepartitionierung T2 - Frühjahrstreffen der Fachgruppen Betriebssysteme, Hannover, 2. März 2018 Y1 - 2018 UR - https://www.betriebssysteme.org/wp-content/uploads/2018/04/fgbs18-169.pdf ER - TY - GEN A1 - Mauerer, Wolfgang T1 - Safety, Security, Quality: Artificial Intelligence versus Common Sense T2 - Open Source Summit North America and Embedded Linux Conference North America 2020 Y1 - 2020 UR - https://www.youtube.com/watch?v=Ow_tMneQlH4 UR - https://elinux.org/images/7/7d/Wolfgang_Mauerer.pdf ER - TY - GEN A1 - Ramsauer, Ralf A1 - Kiszka, Jan A1 - Mauerer, Wolfgang T1 - Spectre and Meltdown vs. Real-Time: How Much do Mitigations Cost? T2 - Embedded Linux Conference Europe 2018, October 22 - 24, 2018, Edinburgh, UK Y1 - 2018 UR - https://www.youtube.com/watch?v=nqU4j2M_Ul4 ER - TY - GEN A1 - Mauerer, Wolfgang T1 - Open Source in Research and Reality T2 - Open Source Summit North America and Embedded Linux Conference North America 2020 Y1 - 2020 UR - https://www.youtube.com/watch?v=L2iubyD1e7U ER - TY - GEN A1 - Ramsauer, Ralf A1 - Lohmann, Daniel A1 - Mauerer, Wolfgang T1 - Quantifying Upstream Integration with PaStA T2 - LTSI Workshop @ ELC17 Y1 - 2017 ER - TY - GEN A1 - Mauerer, Wolfgang T1 - Approaches to Ultra Long-Term System Maintenance T2 - Embedded Linux Conference Europe (Berlin), 2016 Y1 - 2016 UR - https://www.youtube.com/watch?v=SAbrQqSC61M ER - TY - GEN A1 - Mauerer, Wolfgang T1 - Socio-Technical Aspects of Long Term Embedded Systems Maintenance T2 - Embedded Linux Conference, April 4-6, 2016, San Diego Y1 - 2016 ER - TY - GEN A1 - Mintel, Mario A1 - Ramsauer, Ralf A1 - Lohmann, Daniel A1 - Scherzinger, Stefanie A1 - Mauerer, Wolfgang T1 - Fork à la carte für In-Memory-Datenbanken T2 - Frühjahrstreffen der Fachgruppen Betriebssysteme, Hamburg, 17. März 2022 Y1 - 2022 UR - https://www.lfdr.de/Publications/2022/FGBS_Spring22_Mintel.pdf ER - TY - GEN A1 - Mauerer, Wolfgang A1 - Ramsauer, Ralf A1 - Kölbl, Andreas T1 - The Many Approaches to Real-Time and Safety-Critical Linux T2 - Open Source Summit Japan 2017 Y1 - 2017 UR - http://events17.linuxfoundation.org/sites/events/files/slides/talk_10.pdf ER - TY - GEN A1 - Bielmeier, Benno A1 - Mauerer, Wolfgang T1 - Semi-Formal Verification of Embedded Linux Systems Using Trace-Based Models T2 - Semi-Formal Verification of Embedded Linux Systems Using Trace-Based Models Y1 - 2023 UR - https://www.lfdr.de/Publications/2022/bielmeier_ossj22.pdf UR - https://www.youtube.com/watch?v=w42ab8-CH1o ER - TY - GEN A1 - Mauerer, Wolfgang A1 - Wagner, Daniel T1 - Cyclic Tests Unleashed: Large-Scale RT Analysis with Jitterdebugger T2 - Open Source Summit Japan (Tokio) and OSSNA 17.07.2019 Y1 - 2019 UR - https://events19.linuxfoundation.org/wp-content/uploads/2018/07/talk.pdf ER - TY - JOUR A1 - Schönberger, Manuel A1 - Scherzinger, Stefanie A1 - Mauerer, Wolfgang T1 - Ready to Leap (by Co-Design)? Join Order Optimisation on Quantum Hardware JF - Proceedings of the ACM on Management of Data, PACMMOD N2 - The prospect of achieving computational speedups by exploiting quantum phenomena makes the use of quantum processing units (QPUs) attractive for many algorithmic database problems. Query optimisation, which concerns problems that typically need to explore large search spaces, seems like an ideal match for the known quantum algorithms. We present the first quantum implementation of join ordering, which is one of the most investigated and fundamental query optimisation problems, based on a reformulation to quadratic binary unconstrained optimisation problems. We empirically characterise our method on two state-of-the-art approaches (gate-based quantum computing and quantum annealing), and identify speed-ups compared to the best know classical join ordering approaches for input sizes that can be processed with current quantum annealers. However, we also confirm that limits of early-stage technology are quickly reached. Current QPUs are classified as noisy, intermediate scale quantum computers (NISQ), and are restricted by a variety of limitations that reduce their capabilities as compared to ideal future quantum computers, which prevents us from scaling up problem dimensions and reaching practical utility. To overcome these challenges, our formulation accounts for specific QPU properties and limitations, and allows us to trade between achievable solution quality and possible problem size. In contrast to all prior work on quantum computing for query optimisation and database-related challenges, we go beyond currently available QPUs, and explicitly target the scalability limitations: Using insights gained from numerical simulations and our experimental analysis, we identify key criteria for co-designing QPUs to improve their usefulness for join ordering, and show how even relatively minor physical architectural improvements can result in substantial enhancements. Finally, we outline a path towards practical utility of custom-designed QPUs. KW - Hardware KW - Quantum cmputation KW - Informations systems KW - Join algorithms Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-56634 N1 - Corresponding author: Manuel Schönberger VL - 1 IS - 1 SP - 1 EP - 27 PB - ACM CY - New York, NY, ER - TY - CHAP A1 - Ramsauer, Ralf A1 - Lohmann, Daniel A1 - Mauerer, Wolfgang T1 - The List is the Process: Reliable Pre-Integration Tracking of Commits on Mailing Lists T2 - 2019 IEEE/ACM 41st International Conference on Software Engineering (ICSE), 25-31 May 2019, Montreal, QC, Canada N2 - A considerable corpus of research on software evolution focuses on mining changes in software repositories, but omits their pre-integration history. We present a novel method for tracking this otherwise invisible evolution of software changes on mailing lists by connecting all early revisions of changes to their final version in repositories. Since artefact modifications on mailing lists are communicated by updates to fragments (i.e., patches) only, identifying semantically similar changes is a non-trivial task that our approach solves in a language-independent way. We evaluate our method on high-profile open source software (OSS) projects like the Linux kernel, and validate its high accuracy using an elaborately created ground truth. Our approach can be used to quantify properties of OSS development processes, which is an essential requirement for using OSS in reliable or safety-critical industrial products, where certifiability and conformance to processes are crucial. The high accuracy of our technique allows, to the best of our knowledge, for the first time to quantitatively determine if an open development process effectively aligns with given formal process requirements. KW - commits KW - Data mining KW - Electronic mail KW - Linux KW - mailing lists KW - mining software repositories KW - Open source software KW - patches KW - Software engineering KW - Software maintenance KW - Software reliability Y1 - 2019 U6 - https://doi.org/10.1109/ICSE.2019.00088 SP - 807 EP - 818 PB - IEEE ER - TY - CHAP A1 - Mauerer, Wolfgang A1 - Scherzinger, Stefanie ED - Ailamaki, Anastasia T1 - Nullius in Verba: Reproducibility for Database Systems Research, Revisited T2 - 2021 IEEE 37th International Conference on Data Engineering (ICDE 2021): 19-22 April 2021, Chania, Greece N2 - Over the last decade, reproducibility of experimental results has been a prime focus in database systems research, and many high-profile conferences award results that can be independently verified. Since database systems research involves complex software stacks that non-trivially interact with hardware, sharing experimental setups is anything but trivial: Building a working reproduction package goes far beyond providing a DOI to some repository hosting data, code, and setup instructions.This tutorial revisits reproducible engineering in the face of state-of-the-art technology, and best practices gained in other computer science research communities. In particular, in the hands-on part, we demonstrate how to package entire system software stacks for dissemination. To ascertain long-term reproducibility over decades (or ideally, forever), we discuss why relying on open source technologies massively employed in industry has essential advantages over approaches crafted specifically for research. Supplementary material shows how version control systems that allow for non-linearly rewriting recorded history can document the structured genesis behind experimental setups in a way that is substantially easier to understand, without involvement of the original authors, compared to detour-ridden, strictly historic evolution. KW - Control systems KW - Data engineering KW - Database systems KW - docker KW - git KW - Hardware KW - Industries KW - Reproducibility of results KW - reproducible science KW - reproduction, reproduction package KW - scientific attribution KW - scientific method KW - Tutorials Y1 - 2021 SN - 978-1-7281-9184-3 U6 - https://doi.org/10.1109/ICDE51399.2021.00270 SP - 2377 EP - 2380 PB - IEEE CY - Piscataway, NJ ER - TY - CHAP A1 - Mauerer, Wolfgang A1 - Ramsauer, Ralf A1 - Lucas, Edson R. F. A1 - Scherzinger, Stefanie T1 - Silentium! Run-Analyse-Eradicate the Noise out of the DB/OS Stack T2 - Datenbanksysteme für Business, Technologie und Web (BTW 2021): 13.-17. September 2021, Dresden, Deutschland N2 - When multiple tenants compete for resources, database performance tends to suffer. Yet there are scenarios where guaranteed sub-millisecond latencies are crucial, such as in real-time data processing, IoT devices, or when operating in safety-critical environments. In this paper, we study how to make query latencies deterministic in the face of noise (whether caused by other tenants or unrelated operating system tasks). We perform controlled experiments with an in-memory database engine in a multi-tenant setting, where we successively eradicate noisy interference from within the system software stack, to the point where the engine runs close to bare-metal on the underlying hardware. We show that we can achieve query latencies comparable to the database engine running as the sole tenant, but without noticeably impacting the workload of competing tenants. We discuss these results in the context of ongoing efforts to build custom operating systems for database workloads, and point out that for certain use cases, the margin for improvement is rather narrow. In fact, for scenarios like ours, existing operating systems might just be good enough, provided that they are expertly configured. We then critically discuss these findings in the light of a broader family of database systems (e.g., including disk-based), and how to extend the approach of this paper accordingly. Low-latency databases; tail latency; real-time databases; bounded-time query processing; DB-OS co-engineering KW - bounded-time query processing KW - DB-OS co-engineering KW - Low-latency databases KW - real-time databases KW - tail latency Y1 - 2021 U6 - https://doi.org/10.18420/btw2021-21 SP - 397 EP - 421 PB - Gesellschaft für Informatik ER - TY - JOUR A1 - Franz, Maja A1 - Wolf, Lucas A1 - Periyasamy, Maniraman A1 - Ufrecht, Christian A1 - Scherer, Daniel D. A1 - Plinge, Axel A1 - Mutschler, Christopher A1 - Mauerer, Wolfgang T1 - Uncovering Instabilities in Variational-Quantum Deep Q-Networks JF - Journal of the Franklin Institute N2 - Deep Reinforcement Learning (RL) has considerably advanced over the past decade. At the same time, state-of-the-art RL algorithms require a large computational budget in terms of training time to converge. Recent work has started to approach this problem through the lens of quantum computing, which promises theoretical speed-ups for several traditionally hard tasks. In this work, we examine a class of hybrid quantumclassical RL algorithms that we collectively refer to as variational quantum deep Q-networks (VQ-DQN). We show that VQ-DQN approaches are subject to instabilities that cause the learned policy to diverge, study the extent to which this afflicts reproduciblity of established results based on classical simulation, and perform systematic experiments to identify potential explanations for the observed instabilities. Additionally, and in contrast to most existing work on quantum reinforcement learning, we execute RL algorithms on an actual quantum processing unit (an IBM Quantum Device) and investigate differences in behaviour between simulated and physical quantum systems that suffer from implementation deficiencies. Our experiments show that, contrary to opposite claims in the literature, it cannot be conclusively decided if known quantum approaches, even if simulated without physical imperfections, can provide an advantage as compared to classical approaches. Finally, we provide a robust, universal and well-tested implementation of VQ-DQN as a reproducible testbed for future experiments. KW - Artificial Intelligence KW - Computer Science KW - Quantum Physics Y1 - 2022 U6 - https://doi.org/10.1016/j.jfranklin.2022.08.021 SN - 0016-0032 N1 - Corresponding author: Maja Franz PB - Elsevier ET - In Press, Corrected Proof ER - TY - JOUR A1 - Sax, Irmi A1 - Feld, Sebastian A1 - Zielinski, Sebastian A1 - Gabor, Thomas A1 - Linnhoff-Popien, Claudia A1 - Mauerer, Wolfgang T1 - Towards Understanding Approximation Complexity on a Quantum Annealer JF - Digitale Welt N2 - Many industrially relevant problems can be deterministically solved by computers in principle, but are intractable in practice, as the seminal P/NP dichotomy of complexity theory and Cobham’s thesis testify. For the many NP-complete problems, industry needs to resort to using heuristics or approximation algorithms. For approximation algorithms, there is a more refined classification in complexity classes that goes beyond the simple P/NP dichotomy. As it is well known, approximation classes form a hierarchy, that is, FPTAS \subseteq PTAS \subseteq APX \subseteq NPO. This classification gives a more realistic notion of complexity but—unless unexpected breakthroughs happen for fundamental problems like P = NP or related questions— there is no known efficient algorithm that can solve such problems exactly on a realistic computer. Therefore, new ways of computations are sought. Recently, considerable hope was placed on the possible computational powers of quantum computers and quantum annealing (QA) in particular. However, the precise benefits of such a drastic shift in hardware are still unchartered territory to a good extent. Firstly, the exact relations between classical and quantum complexity classes pose many open questions, and secondly, technical details of formulating and implementing quantum algorithms play a crucial role in real-world applications. Guided by the hierarchy of classical optimisation complexity classes, we discuss how to map problems of each class to a quantum annealer. Those problems are the Minimum Multiprocessor Scheduling (MMS) problem, the Minimum Vertex Cover (MVC) problem and the Maximum Independent Set (MIS) problem. We experimentally investigate if and how the degree of approximability influences implementation and run-time performance. Our experiments indicate a discrepancy between classical approximation complexity and QA behaviour: Problems MIS and MVC, members of APX respectively PTAS, exhibit better solution quality on a QA than MMS, which is in FPTAS, even despite the use of preprocessing the for latter. This leads to the hypothesis that traditional classifications do not immediately extend to the quantum annealing domain, at least when the properties of real-world devices are taken into account. A structural reason, why FPTAS problems do not show good solution quality, might be the use of an inequlity in the problem description of the FPTAS problems. Formulating those inequalities on a quantum hardware (mostly done by formulating a Quadratic Unconstrained Binary optimisation (QUBO) problem in form of a matrix) requires a lot of hardware space which makes finding an optimal solution more difficult. Reducing the density of a QUBO is possible by appropriately pruning QUBO matrices. For the problems considered in our evaluation, we find that the achievable solution quality on a real-world machine is unexpectedly robust against pruning, often up to ratios as high as 50% or more. Since quantum annealers are probabilistic machines by design, the loss in solution quality is only of subordinate relevance, especially considering that the pruning of QUBO matrices allows for solving larger problem instances on hardware of a given capacity. We quantitatively discuss the interplay between these factors. Y1 - 2020 U6 - https://doi.org/10.1007/s42354-019-0244-1 VL - 4 IS - 1 SP - 104 PB - DIGITALE WELT Academy c/o Ludwig-Maximilians-Universität München CY - München ER - TY - CHAP A1 - Mauerer, Wolfgang A1 - Scherzinger, Stefanie ED - Krusche, Stephan ED - Wagner, Stefan T1 - Educating Future Software Architects in the Art and Science of Analysing Software Data. T2 - SEUH 2020: Software Engineering im Unterricht der Hochschulen, Tagungsband des 17. Workshops "Software Engineering im Unterricht der Hochschulen", Innsbruck, Österreich, 26. - 27.02.2020 N2 - We report the design and teaching experience of a Master-level seminar course on quantitative and empirical software engineering. The course combines elements of traditional literature seminars with active learning by scientific project work, in particular quantitative mixed-method analyses of open source systems. It also provides short introductions and refreshers to data mining and statistical analysis, and discusses the nature and practice of scientific knowledge inference. Student presentations of published research, augmented by summary reports, bridge to standard seminars. We discuss our educational goals and the course structure derived from them. We review research questions addressed by students in mini research reports, and analyse them as tokens on how junior-level software engineers perceive the potential of empirical software engineering research. We assess challenges faced, and discuss possible solutions. Y1 - 2020 UR - http://ceur-ws.org/Vol-2531/paper10.pdf SP - 56 EP - 60 PB - RWTH Aachen ER - TY - INPR A1 - Ramsauer, Ralf A1 - Huber, Stefan A1 - Schwarz, Konrad A1 - Kiszka, Jan A1 - Mauerer, Wolfgang T1 - Static Hardware Partitioning on RISC-V - Shortcomings, Limitations, and Prospects N2 - On embedded processors that are increasingly equipped with multiple CPU cores, static hardware partitioning is an established means of consolidating and isolating workloads onto single chips. This architectural pattern is suitable for mixed-criticality workloads that need to satisfy both, real-time and safety requirements, given suitable hardware properties. In this work, we focus on exploiting contemporary virtualisation mechanisms to achieve freedom from interference respectively isolation between workloads. Possibilities to achieve temporal and spatial isolation-while maintaining real-time capabilities-include statically partitioning resources, avoiding the sharing of devices, and ascertaining zero interventions of superordinate control structures. This eliminates overhead due to hardware partitioning, but implies certain hardware capabilities that are not yet fully implemented in contemporary standard systems. To address such hardware limitations, the customisable and configurable RISC-V instruction set architecture offers the possibility of swift, unrestricted modifications. We present findings on the current RISC-V specification and its implementations that necessitate interventions of superordinate control structures. We identify numerous issues adverse to implementing our goal of achieving zero interventions respectively zero overhead: On the design level, and especially with regards to handling interrupts. Based on micro-benchmark measurements, we discuss the implications of our findings, and argue how they can provide a basis for future extensions and improvements of the RISC-V architecture. Y1 - 2022 U6 - https://doi.org/10.48550/arXiv.2208.02703 ER - TY - INPR A1 - Oberthür, S. A1 - Mauerer, Wolfgang T1 - Sicherheit von Android-Systemen Y1 - 2012 ER - TY - CHAP A1 - Mauerer, Wolfgang T1 - Supershrink Linux – and beyond T2 - Embedded Linux Conference Europe (Dublin), 2015 Y1 - ER - TY - CHAP A1 - Scherzinger, Stefanie A1 - Mauerer, Wolfgang A1 - Kondylakis, Haridimos ED - Ailamaki, Anastasia T1 - DeBinelle: Semantic Patches for Coupled Database-Application Evolution T2 - 2021 IEEE 37th International Conference on Data Engineering (ICDE 2021): 19-22 April 2021, Chania, Greece N2 - Databases are at the core of virtually any software product. Changes to database schemas cannot be made in isolation, as they are intricately coupled with application code. Such couplings enforce collateral evolution, which is a recognised, important research problem. In this demonstration, we show a new dimension to this problem, in software that supports alternative database backends: vendor-specific SQL dialects necessitate a simultaneous evolution of both, database schema and program code, for all supported DB variants. These near-same changes impose substantial manual effort for software developers. We introduce DeBinelle, a novel framework and domain-specific language for semantic patches that abstracts DB-variant schema changes and coupled program code into a single, unified representation. DeBinelle further offers a novel alternative to manually evolving coupled schemas and code. DeBinelle considerably extends established, seminal results in software engineering research, supporting several programming languages, and the many dialects of SQL. It effectively eliminates the need to perform vendor-specific changes, replacing them with intuitive semantic patches. Our demo of DeBinelle is based on real-world use cases from reference systems for schema evolution. KW - database management systems KW - databases KW - evolution KW - programming language semantics KW - semantic patches KW - software product lines KW - specification languages KW - SQL Y1 - 2021 SN - 978-1-7281-9184-3 U6 - https://doi.org/10.1109/ICDE51399.2021.00307 SP - 2697 EP - 2700 PB - IEEE CY - Piscataway, NJ ER -